It is known to provide such a fuel injector with an external filter means disposed to filter the fuel as it approaches the fuel injector's inlet. While such a filter is suitable for preventing particulate material in fuel from entering the fuel injector, it is incapable of filtering particulate material that may originate internally of the fuel injector either on account of processes used to manufacture and assemble the fuel injector or on account of usage.
The present invention relates to an improvement that enables a filter to be disposed internally of the fuel injector between the inlet and the internal valve means so that particulate material having an internal origin may also be prevented from reaching the valve means.
Although it is known to provide certain mechanical fuel injectors with flow geometries intended to filter particulate material of external origin, insofar as the applicant is aware the issue of filtering particulate material that originates internally of an electromechanical actuated gasoline, or flex fuel, fuel injector has not been successfully addressed. Such fuel injectors are typically manufactured in special environments using special processes to eliminate sources of contamination inside the finished product. Particulate material can originate within such a fuel injector due to manufacturing processes and/or from inadequate cleaning of component parts prior to assembly. Internal particulate material can originate from any assembly tooling, gauging, or air borne matter which becomes trapped inside the fuel injector prior to assembly of the external filter at the fuel injector inlet. Elimination of sources of internal contamination has historically been controlled only through special manufacturing processes, special techniques, and parts inspection.
The present invention is not intended to eliminate the need to maintain certain process controls used to avoid the inclusion of particulate material in the finished fuel injector. The invention is, however, intended to possibly minimize the intensity of inspection that may be required of the fuel injector and its component parts during assembly and thus more efficiently satisfy requirements against internal contamination.
Briefly, the present invention comprises in a general way the incorporation of an internal filter element in close proximity to the fuel injector's valve means. Thus, any particulate material greater than a certain size and originating internally of the fuel injector either after assembly or during use of the fuel injector will be prevented from reaching the internal valve means and thus possibly interfering with the proper functioning of the fuel injector. The preferred embodiment of the invention comprises for the filtering element an electroformed metal filter screen element. A preferred embodiment of the invention applied to a particular fuel injector will be disclosed and in this embodiment the arrangement is especially advantageous because of the manner in which the filter element is associated with the individual component parts of that particular fuel injector. Principles of the invention are, however, applicable to embodiments of gasoline, or flex fuel, fuel injectors other than the particular embodiment that is disclosed herein.
Further features, advantages and benefits of the invention, along with those already mentioned, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings illustrate a presently preferred embodiment of the invention according to the best mode contemplated at this time for carrying out the invention.